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E. M. SAWTELLE WOOD DiSTJLLATI ON. APPLICATION FILED SEPT. 10, 1918 ahvewto c M v luau tug 5*" Patented M11112, 1921.

I known as a 50 B. H. P. producer. lts lower part is ironshelled with a brick lining and;

without loss an d UNITED s rres- PATENT OFFICE.

EDMUND M. sawrnnrn, or'nnetnwoozo, new JERSEY, AssrGNoR To JULIUS R onnrnn, or ennnnwrcn, oonnncrronr, AND nonnn'r L. saunas, or LAW- RENGEBURG, INDIANA.

WOOD DISTILLATION.

Specification of Letters Patent. Patented Apr. 12, 1921. i

Application filed September 10, 1918. Serial No. 253,367.

To all 2071 am it may concern Be it known that I, EDMUND M. SAw'rnLLn, citizen of the United States, residing in lfi nglewood, New Jerse have invented the following-described Improvements in Nood Distillation.

The invention is a process of destructive distillation of wood for the production of pyroligneous acid and Wood-tar products and combustible gas. Such products have heretofore been manufactured principally by distillation in closed retorts wherein the wood is isolated from the combustion which furnishes the initial heat. It has also been proposed to condense such products from the fume from charcoal kilns and from so called wood-gaspreducers wherein the heat is furnished by progressive partial combustion of the wood itself. In these processes, as thus far attempted, the acid yield has been so limited as compared to the retort process, that they have not been considered practicable or capable of being carried 011 with profit, even wherea by-product conibustiblc gas of some value has been included in the recovery from the wood. The present invention belongs to this latter class of distillation processes and resides in the method of control of the combustion and in the treatment of the wood fume in such manner that the yield compares favorably with that from the retort process, or any other process, being produced from cheaper materials by a continuous operation and at less expense and whereby also a combustile is produced, of distinct value, 1n

greater or less proportion according to the kind of wood used and the regulation of the process.

The new process, while continuous in char actor, as above mentioned, affords the further advantage that the distillation may be checked for over night stand-by periods possibly in some instances with economy.

The accompanying drawing represents an actual installation of commercial size which I have successfully used for carrying out the process:

Such apparatus comprises a cylindricalproducer gas furnace designed by its manufacturers for anthracite pea-coal and I and ash pit, the interior chamber above the grate being about 33' inches diameter and 6 feet high; No air enters this chamber save through the grate, from a regulated opening 2, 1n the delivery pipe from a small hand blower 3 which is provided in the ash pit for temporarily increasing the air draft whenC-ptarting the process or after a standby perio The wood to be distilled is introduced through the feed hopper from a' suitable supply reservoir as indicated in the drawing and in the form of small pieces substantially the same as found. in ordinary planer mill waste, that is to say, in the form of pieces about a square inch in surface area and onequarter inch or less thick, intermixed with. fine particles or saw-dust. When the wood,

as received, contains larger pieces to any considerable extent or blocks or slabs, they are preferably run through a hogging machine such as commonlyused in pulp mills and thereby reduced to substantially the size indicated. \For the sizefof furnace under description it is preferred that the wood be composed of about 70% of the hogged or large size chips and 30% of Sill/V". dust although considerable variation from these proportions and from the said dimensions of chips is permissible under different conditions. In general, the larger the furnace the larger may be the size of the Wood pieces. Limb wood, brush, and other forms of wood refuse may also be reduced to the form stated and used in this process either with or without mixturewith saw-dust or other material. Uniformity and substantial homogeneity of mixtureis important. 7

When initially setting the apparatus in operation, a layer of dead clinkers is first laid on the grate to keep the wood from falling through and to distribute the air supply, and a fire is kindled thereon in the I connected tothe end of the condenser system. By the use of the double doors in the feed hopper at the top of the furnace, additional wood may be fed in as the distillation proceeds without opening the furnace chamber to external atmosphere and thereby disturbing the draft or pressure condition therein. A poker shown in dotted line may be inserted through the roof at one or more points around the feed doors. This poker is used when necessary during distillation to keep the mass in a uniformly homogeneous condition free from bridges and so-called chimneys or flue holes. The points for entrance for the poker through the furnace roof are arranged so as to allow its insertion and withdrawal without opening a vent to the interior of the furnace.

The draft through the wood mass being regulated by adjustment of the throttle 2 to a critical point as later explained, the outflow is through an off-take 5 to the condenser system which comprises first a trap chamber 6 of commodious proportions varying with the size of the producer and say about 3 feet in diameter in the present case. It is provided with a central depending baffie wall and a drainage outlet at its bottom which outlet is normally sealed by submersion in a liquor receptacle 7 so that outside air may not enter the system while the liquid condensing therein may escape and flow to the receptacle A. The same outlet acts as a safety valve to relieve any sudden expansion of gases within the system. The primary function of the trap chamber 6 is to collect and remove suspended solid matter from the fume for which reason it is relatively large and it is also preferably waterjacketed so that it serves to condense some tar and pyroligneous liquor from the furnace eflluent, said liquor flowing through the outlet to the receptacle A. From this chamber the furnace efiluent passes upwardly into the first condensing leg 8 and thence successively through a shut-off valve 9, a depending leg 10, an ascending leg 12 and a descending leg 14 to the first scrubber 16 and thence to a final scrubber 17 Water at street main temperature is conducted by pipe 18 under regulation by the valves 18, to a shower head 19 applied to the top of each leg and so as to deliver water as a film over the outside of each leg flowing off thence through the basins 20. Liquor condensing in the leg 8 flows by gravity to the receptacle A. The liquor condensing in each of the other legs escapes therefrom through similarly sealed outlets 11, 13 and 15 respectively arran ed to deliver to receptacles 13,0 and D. Each of the condensing legs is of copper about 6 inches in diameter and 20 feet long, (except leg 8 which is somewhat shorter), but the size and number of the legsmay vary with the capacity of the furnace, it being important only that there be enough of them to cool the gas to normal, room temperature while in transit through the system.

The first scrubber 16 is packed with broken glass or similar material and provided with a liquid outlet sealed against entrance of outside air like the other legs. It delivers collected liquor through such outlet to the receptacle B. This scrubber 16 may be from 10 to 16 inches in diameter and about 20 feet long accordin to the capacity of the furnace and is pre erably kept at ordinary room temperature. The final scrubber 17 is of larger; internal capacity being approximately 6 feet in diameter and contains interior shelves or partitions, the lowermost of which carries a bed of broken glass or similar suitable substance 26 and the uppermost of which carries a bed of wood shavings. The interior of this scrubber may also contain appropriate liquid solutions for effecting the scrubbing operation or for the purpose of imparting some desiredj quality to the exhausted effluent. The gaseous flow from the first scrubber enters the second scrubber near its bottom and flows upwardly therein through the glass and shavings. By reason of the large size of the scrubber 17 the velocity of flow is considerably reduced. Collected liquor flows to the liquor receptacle F. The upper end of leg 8 is connected through a valve 21 with a purge pipe through which the furnace fume can be vented to atmosphere when the exhauster is not running or whenever desired. Manometers 25 are provided at different points in the system to indicate the internal pressure. The large scrubber 17 and the chamber 6 and other portions of the system are provided with clean-out hand holes as indicated at 28. The exhauster apparatus I have used with success is one which at about 7 3 R. P. M. will move about- 6% cubic feet of free air per minute.

In operation of the apparatus described the exhauster is set in operation with proper regulation of speed to maintain an internal minus pressure condition of not over one inch of water in the furnace, the throttle 2 being regulated accordingly and the cor rect adjustment will be indicated by a maximum evolution of smoke from the wood at the lowest temperature that will keep up a condition of uniform combustion and distillation in the furnace according to requirements. Air only enters the bottom of the stack; no additional medium such as steam or water vapor is necessary or supplied.

Additional wood is fed in small amounts indicated by the size of the feed hopper to the interior of the furnace, to maintain a substantially constant level therein. The entire effluent produced by the furnace, including the acid, tar, steam, CO and CO is conducted through the same path through the condenser system wherein it acquires a progressively lower temperature. The condensate resulting from the successive cooling effect in the difierent legs or sections is collected separately in each of the several liquor receptacles provided for the pun pose. This separate collection or fractional condensation of the fume results in aspecial economy in that the liquor product in some of the receptacles varies in acid content which acid can therefore be removed. with corresponding efficiency in the subsequent treatment for example, in the average case but always varying to some extent with the character of wood used, the liquor considered in terms of contained acetic acid yields in each receptacle as follows:

Receptacle Al0% acetic acid.

maintained pyroligneous liquor accumulates in the entire series of receptacles in the proportion of about 40 to of the weight of the wood, usually better than 50% and it will be observed that this yield compares most favorably with the closed retort method besides having the advantage of operating on wood waste and of being continuous. The distillation although continuous, as above described, may be checked or stopped over night or other period whenever desired by opening the valve 21 to the purge pipe 23 whereupon the then natural draft through the furnace is adjusted to keep the fire going, production of liquor being promptly resumed in the morning when a proper draft and pressure condition is again restored.

Claims.

1. The process of destructively distilling woodwhich consists in maintaining a descending progressively replenished mass of sub-divided wood and a condition of limited, regulated combustion in the lower part of said mass in the absence of introduced steam, withdrawing the combustion and distillation efliuents upwardly through said mass, and conducting the whole of said efr'luents through a condensing system and therein. separating the pyroligneous liquor therefrom.

2. The process of destructively distilling wood which consists in maintaining a condition of partial combustion in a progressively replenished and hence substantially constant mass of co-mminuted wood in the absence of introduced steam conductin the I entire eilluent therefrom through a condensing system and separately collecting the liquor condensed in different portions or sections of said system.

3. The process of destructively distilling wood which consists in the maintaining by intermittent replenishment a substantially constant mass of comminuted wood and a condition of partial combustion in its lower region at a minus pressure in the absence of introduced steam, withdrawing the whole effluent resulting from such combustion through a condenser system and fractionally condensing the liquor therefrom.

4c. The process of destructively distilling wood which consists in maintaining a progressively replenished mass of subdivided wood in a suitable closed chamber and a condition of continuous restricted combustion in the lower part of said mass in the the absence of introduced steam, the said combustion being regulated to produce an eflluent comprising a combustible gas and pyroligneous vapor, withdrawing said effluent upwardly through said mass and conducting the whole of said efiiuent from the top of said chamber through a condensing system wherein the pyroligneous liquor is collected and the combustible gas discharged.

5. The process of destructively distilling wood, which consists in comminuting the wood into pieces of substantially planer mill shaving size, maintaining a progres sively replenished stack or mass of such wood in a suitable chamber and a condition of limited combustion in the lower part of said mass in the absence of introduced steam, regulating the admission of air to the mass to maintain a maximum smoke pro duction therein, withdrawing the smoke effluent through the mass and condensing the same to separate it into pyroligneous liquor and a combustible gas.

6. The process of destructively distilling wood, which consists in subjecting a substantially constant mass of wood in subdivided form to partial combustion in a closed chamber under minus pressure and in the absence of introduced steam or water vapor by admitting a continuous restricted flow of air to said chamber, conducting combustion and distillation effluents therefrom through a cooled passage and thence through a scrubbing apparatus, collecting the combustible from said passage and scrubber, and withdrawing the combustible gas from the scrubber.

In testimony whereof I have signed this specification.

EDMUND M. SAWTELLE. 

